Angular velocity sensor correcting apparatus and method

1. An angular velocity sensor correcting apparatus, including a processor and a memory storing a program for execution by the processor, the program comprising: an obtaining module for obtaining measurement data of an object measured on the basis of a signal from a GPS satellite, and for obtaining angular velocity of the object output from an angular velocity sensor; an estimating module for estimating a running condition of the object on the basis of the measurement data and the angular velocity obtained by the obtaining module; an offset value deriving module to sequentially derive a temporary offset value of the angular velocity sensor while changing combination of the measurement data and the angular velocity obtained by the obtaining module in accordance with the running condition of the object estimated by the estimating module; and an offset value filter process module operative to derive an offset value of the angular velocity sensor for correcting the angular velocity output from the angular velocity sensor by executing a statistical process on the temporary offset value of the angular velocity sensor, the temporary offset value sequentially derived by the offset value deriving module, wherein the estimating module estimates that the running condition of the object is either a first state, in which the object stops or runs straight, or a second state, wherein the offset value deriving module sequentially derives a temporary offset value of the angular velocity sensor on the basis of the angular velocity obtained by the obtaining module when the estimating module estimates that the running condition of the object is the first state, and the offset value deriving module sequentially derives the temporary offset value of the angular velocity sensor on the basis of the measurement data and the angular velocity obtained by the obtaining module when the estimating module estimates that the running condition of the object is the second state, and wherein the offset value filter process module changes a forgetting factor in the statistical process in accordance with the running condition of the object estimated by the estimating module, and the offset value filter process module uses a forgetting factor by which influence of the temporary offset value obtained in the past, in derivation of the offset value of the angular velocity sensor in the first state becomes smaller than that in the second state in the statistical process.

2. The angular velocity sensor correcting apparatus of claim 1 , wherein the measurement data obtained by the obtaining module includes velocity of the object, wherein the estimating module also estimates that the running condition of the object is a third state where the object runs straight, wherein the offset value deriving module sequentially derives a temporary offset value of the angular velocity sensor on the basis of the angular velocity obtained by the obtaining module when the estimating module estimates that the running condition of the object is the first state or the third state, and the offset value deriving module sequentially derives the temporary offset value of the angular velocity sensor on the basis of the measurement data and the angular velocity obtained by the obtaining module when the estimating module estimates that the running condition of the object is the second state, and wherein the offset value filter process module changes a forgetting factor in the statistical process in accordance with the running condition of the object estimated by the estimating module, and the offset value filter process module uses a forgetting factor by which influence of the temporary offset value obtained in the past, in derivation of the offset value of the angular velocity sensor decreases in order of the second state, the third state, and the first state in the statistical process.

3. An angular velocity sensor correcting method, the method comprising: obtaining, by a processor, measurement data of an object on the basis of a signal from a GPS satellite and angular velocity of the object output from an angular velocity sensor; estimating, by a processor, a running condition of the object on the basis of the measurement data and the angular velocity; sequentially deriving, by a processor, a temporary offset value of the angular velocity sensor while changing a combination of the measurement data and the angular velocity obtained in accordance with the estimated running condition of the object; and deriving, by a processor, an offset value of the angular velocity sensor for correcting the angular velocity output from the angular velocity sensor by executing a statistical process on the sequentially derived temporary offset value of the angular velocity sensor, wherein the estimating estimates that the running condition of the object is either a first state in which the object stops or runs straight or a second state, wherein the sequential deriving of a temporary offset value sequentially derives a temporary offset value of the angular velocity sensor on the basis of the obtained angular velocity when the running condition of the object is estimated to be the first state, and the sequential deriving of a temporary offset value sequentially derives the temporary offset value of the angular velocity sensor on the basis of the obtained measurement data and the angular velocity when the running condition of the object is estimated to be the second state, and wherein the deriving of an offset value changes a forgetting factor in the statistical process in accordance with the estimated running condition of the object and uses a forgetting factor by which influence of the temporary offset value obtained in the past, in derivation of the offset value of the angular velocity sensor in the first state becomes smaller than that in the second state in the statistical process.

4. The angular velocity sensor correcting method according to claim 3 , wherein the obtained measurement data includes velocity of the object, wherein the estimating also estimates that the running condition of the object is a third state where the object runs straight, wherein the sequential deriving of a temporary offset value sequentially derives a temporary offset value of the angular velocity sensor on the basis of the obtained angular velocity when the running condition of the object is estimated to be the first state or the third state, and the sequential deriving of a temporary offset value sequentially derives the temporary offset value of the angular velocity sensor on the basis of the obtained measurement data and angular velocity when the running condition of the object is estimated to be the second state, and wherein the deriving of an offset value changes a forgetting factor in the statistical process in accordance with the estimated running condition of the object, and the deriving of an offset value uses a forgetting factor by which influence of the temporary offset value obtained in the past, in derivation of the offset value of the angular velocity sensor decreases in order of the second state, the third state, and the first state in the statistical process.